Music Transposer Calculator — Transpose Notes by Semitones
Enter a starting note and the number of semitones to transpose (positive = up, negative = down). The calculator shows the resulting note, the interval name for the shift, and the octave displacement — useful for transposing song keys, arranging for transposing instruments, or working out capo positions.
Original note / key
How does this calculator work?
New note = (original semitone + offset) mod 12, where C=0, C♯=1, … B=11. Transposing C up 7 semitones lands on G (Perfect 5th). Transposing B♭ down 2 semitones lands on A♭. Enter note and semitone count to find the transposed note, interval name, and how many octaves shift.
Formula
How this is calculated
Transposition shifts every note in a piece by the same number of semitones, preserving the internal intervals while changing the overall pitch level. Within a single octave the 12 chromatic notes are numbered 0 (C) through 11 (B); adding the semitone offset and taking mod 12 gives the new note, wrapping around the octave boundary as needed. For example, starting at G (semitone 7) and transposing up 7 semitones gives (7+7) mod 12 = 14 mod 12 = 2 = D.
When the total semitone shift exceeds 12, whole octaves are added or subtracted in addition to the within-octave shift. Transposing C up 15 semitones = 12 + 3 semitones = one octave up plus a minor 3rd, landing on E♭ one octave higher. This is useful when arranging for transposing instruments: a B♭ instrument (trumpet, clarinet) sounds one whole step (2 semitones) lower than written, so music for it must be transposed +2 semitones; an E♭ instrument (alto sax) sounds a major 6th lower and is transposed +9 semitones.
This calculator transposes a single note or key root. To transpose a full chord chart, apply the same offset to every chord root and quality independently.
Frequently asked questions
Each fret on a guitar raises pitch by one semitone. A capo on fret 2 transposes the open-string notes up 2 semitones — so chord shapes stay the same but sound 2 semitones higher. To play in D using G-shape chords, set the capo on fret 7 (7 semitones above G = D).
A B♭ instrument sounds one whole step (2 semitones) lower than written. To produce concert pitch C, the player reads D. So to write a part that sounds in concert C, transpose the concert pitch UP by 2 semitones when writing for the trumpet, or enter original = C, semitones = +2 to find the written note (D).
Transposing a key means shifting all notes in a piece by the same number of semitones. This calculator transposes one note at a time; to transpose a full piece or chord progression, apply the same semitone shift to every root note. The quality of chords (major, minor, diminished) is preserved — only the root pitch changes.
Also known as
TG we-Calculate Editorial Team. (2026). Music Transposer Calculator — Transpose Notes by Semitones [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/music-transposer-calculator
TG we-Calculate Editorial Team. "Music Transposer Calculator — Transpose Notes by Semitones." TG we-Calculate. 2026. https://we-calculate.com/calculator/music-transposer-calculator.
TG we-Calculate Editorial Team, "Music Transposer Calculator — Transpose Notes by Semitones," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/music-transposer-calculator
@misc{wecalculate_music_transposer_calculator, title = {Music Transposer Calculator — Transpose Notes by Semitones}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/music-transposer-calculator}}, year = {2026}, note = {TG we-Calculate} }
Did this calculator help you?